You do realize that trance states aren't characterized by visual elements, right? "Vision" is just a poetic description.
Many writers don't make a good distinction between "inner" sight and literal seeing of things when it comes to mystical experiences. It bothers me when I think about it, because I think it sets the wrong kinds of expectations for people interested in things like spellcraft or working with the otherworlds. Language seems very imprecise about many more spiritual/mystical phenomena.